﻿<!DOCTYPE html>
<html>
<head>
  <title>PanelLayout GoJS Sample</title>
  <!-- Copyright 1998-2021 by Northwoods Software Corporation. -->
  <meta name="description" content="Example custom PanelLayout." />
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <script src="../release/go.js"></script>
  <script src="../assets/js/goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
  <script id="code">
    function PanelLayoutCascading() {
      go.PanelLayout.call(this);
    }
    go.Diagram.inherit(PanelLayoutCascading, go.PanelLayout);

    /**
     * Given the available size, measure the Panel and
     * determine its expected drawing size. Sets the measuredBounds of the object.
     *
     * This must call {@link #measureElement} with each Panel element.
     *
     * This must also construct the union.width and union.height of the passed in union Rect argument.
     *
     * @this {PanelLayout}
     * @param {Panel} panel Panel which called this layout
     * @param {number} width expected width of the panel
     * @param {number} height expected width of the panel
     * @param {Array.<GraphObject>} elements Array of Panel elements
     * @param {Rect} union rectangle to contain the expected union bounds of every element in the Panel. Useful for arrange.
     * @param {number} minw minimum width of the panel
     * @param {number} minh minimum height of the panel
     */
    PanelLayoutCascading.prototype.measure = function(panel, width, height, elements, union, minw, minh) {
      var l = elements.length;
      for (var i = 0; i < l; i++) {
        var elem = elements[i];
        this.measureElement(elem, width, height, minw, minh);
        var mb = elem.measuredBounds;
        union.width += mb.width;
        union.height += mb.height;
      }
    }

    /**
     * Given the panel and its list of elements, arrange each element.
     *
     * This must call {@link #arrangeElement} with each Panel element, which will set that element's {@link GraphObject#actualBounds}.
     *
     * For arranging some elements, it is useful to know the total unioned area of every element.
     * This Rect can be used to right-align or center-align, etc, elements within an area.
     *
     * @this {PanelLayout}
     * @param {Panel} panel Panel which called this layout
     * @param {Rect} ar arranged bounds of the panel
     * @param {Array.<GraphObject>} elements Array of Panel elements
     * @param {Rect} union rectangle, if properly constructed in {@link #measure}, that contains the expected union bounds of every element in the Panel.
     */
    PanelLayoutCascading.prototype.arrange = function(panel, elements, union) {
      var l = elements.length;
      var x = 0;
      var y = 0;
      for (var i = 0; i < l; i++) {
        var elem = elements[i];
        var mb = elem.measuredBounds;
        this.arrangeElement(elem, x, y, mb.width, mb.height);
        /*
        * By incrementing the arranged x and y by the width and height, we arrange each object in a diagonal fashion:
        *  A
        *    B
        *      C
        *        D
        */
        x += mb.width;
        y += mb.height;
      }
    }

    // Name and register the PanelLayout, so we can reference it in go.GraphObject.make:
    go.Panel.definePanelLayout('Cascading', new PanelLayoutCascading())


    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
      var $ = go.GraphObject.make;

      myDiagram =
        $(go.Diagram, "myDiagramDiv",
          { "undoManager.isEnabled": true });

      // Define a simple Node template that includes a Cascading Panel holding
      // some number of item Panels holding Shapes, based on data.items being an Array
      // of item descriptor objects.
      myDiagram.nodeTemplate =
        $(go.Node, "Auto",
          { width: 100, height: 100 },
          $(go.Shape,
            { fill: "transparent", strokeWidth: 2 },
            new go.Binding("stroke", "color")),
          $(go.Panel, "Cascading",
            new go.Binding("itemArray", "items"),
            {
              itemTemplate:
                $(go.Panel,
                  $(go.Shape,
                    { width: 20, height: 20, strokeWidth: 0 },
                    new go.Binding("figure", "fig"),
                    new go.Binding("fill", "color"))
                )
            })
        );

      myDiagram.model = new go.GraphLinksModel(
        [
          {
            key: 1,
            color: "lightgreen",
            items: [
              { fig: "RoundedRectangle", color: "lightblue" },
              { fig: "Triangle", color: "pink" }
            ]
          },
          {
            key: 2,
            color: "lightblue",
            items: [
              { fig: "RoundedRectangle", color: "lightgray" },
              { fig: "Square", color: "yellow" },
              { fig: "Circle", color: "orange" }
            ]
          },
          {
            key: 3,
            color: "purple",
            items: [
              { fig: "Diamond", color: "red" }
            ]
          },
          {
            key: 4,
            color: "orange",
            items: [
              { fig: "Circle", color: "green" },
              { fig: "Square", color: "blue" },
              { fig: "Triangle", color: "red" },
              { fig: "TriangleRight", color: "green" }
            ]
          }
        ]);
    }
  </script>
</head>
<body onload="init()">
<div id="sample">
  <!-- The DIV for the Diagram needs an explicit size or else we won't see anything.
       This also adds a border to help see the edges of the viewport. -->
  <div id="myDiagramDiv" style="border: solid 1px black; width:400px; height:400px"></div>
  <p>
    This sample demonstrates creating a simple custom <a>PanelLayout</a>. It merely cascades the elements diagonally,
    as if combining a Horizontal and Vertical panel.
  </p>
  <p>
    Creating your own Panel layouts is very uncommon, and you should not need to create your own to use GoJS effectively.
    However there may be apps that require creating a custom Panel layout because the standard panel layouts
    do not offer the precise behavior that you want.
  </p>
</div>
</body>
</html>
